If the CD had the archives directory in your collection directory you
could use that, but as that is unlikely, the only relatively useful way
you could get the metadata from the burnt cd collection would be to get
the .ldb or .bdb file from it and use the db2txt utiltity which comes
with greenstone to convert the gdbm database to a text form, which
could then be converted into an xml form for import back into
greenstone.

You would have to write a program to convert the text output from gdbm
to xml, perhaps in perl, and this would be perhaps not a trivial
undertaking.

gdbm database file location:

/gsdl/collect/<yourcollectionfolder>/index/text/<yourcollectionfolder>.ldb
or .bdb

db2txt utility location:

on windows:
/gsdl/bin/windows/db2txt.exe

on linux:
/gsdl/bin/linux/db2txt

This is a clunky but possible solution.

One way to not reimport your entire collection every time you add new
data would be to use lucene as your indexer, which supports incremental
building. You cant do this entirely from the GLI, you need to use the
command line, and you need to add -incremental options to import.pl and
buildcol.pl. For more information see: